Improvement in hot-air furnaces



C. B. CHACE.

Hot-Air Furnace.

Patented July 20,1875.

[Ill e111 i101 N. PETERS, PHDTO-UTHOGRAPHER. WASHINGTON D C ETE "rrronCHARLES B. OHAOE, ()F LOOKLAND, OHIO.

IMPROVEMENT IN HOT-AIR FURNACES.

Specification forming part of Letters Patent No. 165,712, dated July 20,1875 application filed November 23, 1874 To all whom it may concern:

Be it known that I, CHARLES E. OHAOE, a resident of the city ofLockland, Hamilton county, State of Ohio, have invented certain new anduseful Improvements in Hot-Air Furnaces, of which the following is aspecification:

My improvements relate to a new and useful construction of hot-airfurnaces, whereby heat is econoniized, the consumption of fuel isrendered very uniform, the furnace is rendered very durable, and theheated air more healthful.

The improvements consist, first, in the connection of the tire-chamberand smoke-flue, with tubes employed for heating the air, the connectionbeing made in such a manner that the products of combustion. shall passfrom the fire-chamber through the tubes on their way to the smoke-flue.

Secondly, in giving such a shape, longitudinally, to these tubes thatthey can expand or contract from or toward the fire-chamber with outrestraint, and giving these tubes, trans versely, such a shape that across-section thereot shows the horizontal width or horizontal diameterof each tube to be less than the vertical height or diameter.

The advantages of this part of my invention are that, as the tubes areflat, and their longest transverse diameter is vertical, the largestamount of air can be presented to the heated metal of the tubes,facilitating the passage of air between the tubes and over theirsurfaces. Furthermore, the flat shape of these tubes enables them to beconstructed of boiler-iron and riveted together in a good, substantial,and durable manner. The longitudinal shape of the tubes and their modeof attachment to their supports, permitting them to expand or contractwithout restraint, prevent the rupture of the tubes or theirconnections.

Thirdly, in arming the brick wall which divides the fire-chamber fromthe heating-chain her with a metallic plate on the heating-chamber side,for the twofold purpose of giving support to the smokeflues, which,being of U- form, are attached to the said plate at both ends, and ofmaking the separation between the fire-chamber and heating-chamber atthe joints of the smoke-fines as complete as possible.

A fourth improvement consists in my improved construction of the brickflues opening from the fire-chamber into the heatingtubes, theirconstruction being such that the flues shall, at their point ofconnection with the heating-tubes, be every way smaller than theadjacent openings of said tubes.

By this arrangement the products of combustion passing through theradiating-tubes do not, at their entrance into said tubes, fall directlyor perpendicularly upon the surfaces of the tubes, and, consequently,the tubes are prevented from being burned. out, and the heat isdistributed with great uniformity over the entire surfaces of saidtubes; and, further, the junction of the extremities of the tubes andthe sustaining-plate are not exposed to the direct action of the fire,thereby rendering it possible to maintain at said juncture a tightjoint.

My fifth improvement consists in a new construction of lines in thefurnace, whereby the air which supplies the combustion shall, whendesired, and before being admitted to the fire-chamben be carriedthrough flues in the brick-work of the furnace, and brought into contactwith heated surfaces and diaphragms forming part of the fire-chamber,whereby it enters the fire-chamber at a high temperature.

This combination secures a more perfect combustion; secondly, itutilizes much of the heat from the fire-chamber, which would otherwisebe dissipated by radiation from the walls.

In the accompanying drawings, Figure 1 is a vertical longitudinalsection. of a furnace constructed according to my invention, saidsection being taken at the dotted line Z Z of Fig. 2. Fig. 2 is avertical transverse section of the same, taken at the dotted line X. Xof Fig. 1, and presenting to view the end of that section which is onthe right hand of Fig. 1. Fig. 3 represents a horizontal section of thebrick flues and ends of the radiating-tubes,-

taken at the dotted line Y Y of Fig. 1; and Fig. 4 represents atransverse vertical section of the radiating-chamber and radiating-tubestherein, taken at the dotted line W of Fig. l.

A designates the brick furnace, containing fire-chamber L, provided witha door, Q, and separated from the ash-pit F by grate M. The ash-pit isprovided with a door, T, and its bottom with a diaphragm, N, preferablyof castiron, separating the pit from a flue, a. Flue a commences at theoutside of the front of the furnace, and, passing under the diaphragm Nand over brick-work beneath, is continued up between the brick-work ofthat wall of the furnace which is opposite to that connected to theheating-tubes. On reaching the top wall of the furnace-flue a turns andruns across the furnace under the top brick-work, and over a diaphragm,P, to that side thereof which is next the heating-tubes. Upon reachingthis latter point it returns under the diaphragm P, and over adiaphragm, j, which latter forms the top of the fire-chamber, and has aflange or lip, h, forming a diaphragm, which extends a short distancedown that side of the firechamber which is opposite to the heatingtubes.The flue (0 extends down between the flange h and the brick-work of thefurnace, and enters the fire-chamber at K. m designates the flues in thebrick-work of the furnace, which connect the tire-chamber and theheatingtubes G, and a designates the flue or passage-way in thebrickwork which connects the heating-tubes and the smoke-flue S.

It may be here remarked that for convenience of manufacture anderection, and the more facile transmission of heat, the diaphragms P, f,and h are of cast-iron.

The entrance or mouth of flue a is provided with a small door, 6, tocontrol the admission of air thereto. B designates the walls of thehot-air chamber, containing the tubes 0. This latter chamber hasentrances t at or near its bottom, for the ingress of air, and outletsV, near its top, for the egress of the same. The heating-tubes O arepreferably of a 3 shape. One mouth of each tube (here the upper one) isattached to the plate D opposite to one of the fines m, so that thecenter of flue m shall be opposite the center of the mouth of the tube,and leave an edge of the flue on every side projecting within the edgesof the mouth of the tube. The other (here the lower mouth ofeach tube)is attached to said plate opposite to the flue m. Flue m is preferablynarrower from top to bottom than the adjacent mouths of theheating-tubes opening thereinto, and is so arranged with reference tothe tubes that at the top and bottom of the said mouth of each tube anedge of the brick-work of said passage-way projects within the top andbottom edges of the mouths of the tube. The plate D is pierced withholes corresponding with and fitting the mouth of the tubes, so as notto interfere with the draft through them. The plate is preferably ofwroughtiron, and the tubes at their months are provided with fl-ngesextending outward at right angles to their length. Bolts 1), or rivets,through these flanges, secure the tubes to the plate D. Plate D isfastened to the brickwork by anchor-bolts, or by it forming one side ofa sheet-iron covering, inclosin g the entire brick-work of thefire-chamber.

The heating-tubes C may be made of any suitable material. When made ofwroughtiron, the tubes may be made in four lengths, one for each side,two of the lengths opposite to one another being flanged outwardly atright angles, and the edges of the other sides opposite to one anotherbeing riveted to said flanges. The shape in crosssection of these tubesis of a figure longer vertically than across horizontally.

The mode in which a furnace containing my improvements operates is asfollows: A fire is first made in chamber L. Should the passage of coldair through the flue a be prevented by means of the flue-door eaforesaid, and the ash-pit door T be opened, the air to supplycombustion will pass through the grate M,and, with the products ofcombustion, will pass into the flues O,-and, passing through them intopassage-way n, find their way thence into smoke-stack S.

When the door T of the ash-pit is closed, and the flue-door e aforesaidisopen, the air to supply combustion will enter the flue a, immediatelybelow the door T, pass under diaphragm N, up through the wall of thefurnace, along under the top of the furnace, and over diaphragm P,thence back between diaphragms P and f, thence down between thebriek-work and diaphragm h, thence it passes into the fire-chamber atabout its middle altitude. This air, in passing through flue a, hassuccessively come into contact with the heated surfaces of the walls anddiaphragms, and has taken up a considerable portionof their heat, andhence, at the time it reaches the fire-chamber, has become highlyheated. It has thus taken up from the walls and diaphragms heat thatwould otherwise have been wasted. This highly-heated air entering thetire-chamber facilitates combustion. The products of combustion now passdirectly through the tines on into the tubes 0. These flues, beingsmaller than the mouths of the tubes, the

v products of combustion do not impinge against the places of junctureof the tubes and the plate D, but pass some distance into the tubesbefore they strike the'interior of the sides of the tubes, and thenimpinge thereon at a very oblique angle and very gently, and their heatis very uniformly and thoroughly distributed over the interior of thesides of the tubes. The juncture of the tubes and the plate is thuspreserved from burning out. The products of combustion now pass directlythrough the tubes, communicating to the latter their heat, and pass intothe passageway n. As the top and bottom edges of the passage-way,respectively, project within and beyond the adjacent edges of theexit-mouth of the tube, said edges are also preserved from burning out.The products of combustion pass from the passage-way a into thesmoke-flue S. The shape of the flues allows them to expand or contractwithout rupture, as the tubes are perfectly free to move away from thefire-chamher or toward it.

The particular shape of tubes here employed is not the only feature ofthis part of my invention; but the principle of my invention ineludesfines of any shape, ,whose months are attached to a common side of thewall inclosing the fire-chamber, and whose shape permits them inexpanding to move from, and in contracting to move toward, other pointsof attachment at the fire-chamber wall without restraint.

The air which is to be heated for entering the apartments enters thehot-air chamber B through the entrances t, and passes up between andaround the tubes 0, and makes its exit through the openings V, fromwhich it is conducted where desired by suitable conduits.

The flat shape of the tubes, as shown in cross-section, enables thelargest amount of heating-surface to be presented to the ascendingcurrents of air.

What I claim as new, and desire to secure by Letters Patent, is

l. The air-induction flue a, formed by furnace bottom, wall, and top,and diaphragms N, P, f, and h, substantially as and for the purposes setforth. r

2. The furnace A, and heating-chamber B, in combination with thesmoke-tubes U, shaped so that, regarding them in cross-section, the

fire-chamber, and free to expand from or contract toward said chamber.

3. The combination of the fine m and the tube 0, the flue being everyway smaller than the tube, and so arranged upon the latter that the edgeof the tube is on every side set back from the edge of the flue, as andfor the purposes set forth.

4. The sustaining-plate D, substantially as described, in combinationwith the j-shaped heating-tubes, and the side of the fire-chain her, forthe purposes set forth.

5. The combination of the hot-air chamber B, forming a chamber distinctfrom the furnace, and constructed with D-sha-ped smokeflues G, by whichthe entire work of heating the air for the distributing-pipes isperformed, cold-air inlets t, and hot-air distributing oriflees V.

6. In combination the chamber B, tubes 0, sustaining-plate D, and afire-chamber, substantially as and for the purposes specified.

7. In combination, a fire-chamber, flue m,

plate D, D-shaped tube 0, in a hot-air chamher, and smokepa'ssag'e waya, substantially as and for the purposes set forth.

'8. In combination, fire-chamber L, ash-pit F, flue a, formed by furnaceand diaphragms N P f h, tlues m, plate D, tubes 0 in hot-air chamber B,and smoke-passage way a, substantially as and forthe purposes set forth.

CHARLES B. GHAOE.

In presence of I). P. KENNEDY, OHAs. MUNROE.

